content/browser/dom_storage/dom_storage_task_runner.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_BROWSER_DOM_STORAGE_DOM_STORAGE_TASK_RUNNER_
   6 #define CONTENT_BROWSER_DOM_STORAGE_DOM_STORAGE_TASK_RUNNER_
   7
   8 #include "base/memory/ref_counted.h"
   9 #include "base/sequenced_task_runner.h"
  10 #include "base/threading/sequenced_worker_pool.h"
  11 #include "base/time/time.h"
  12 #include "content/common/content_export.h"
  13
  14 namespace base {
  15 class MessageLoopProxy;
  16 }
  17
  18 namespace content {
  19
  20 // DOMStorage uses two task sequences (primary vs commit) to avoid
  21 // primary access from queuing up behind commits to disk.
  22 // * Initialization, shutdown, and administrative tasks are performed as
  23 //   shutdown-blocking primary sequence tasks.
  24 // * Tasks directly related to the javascript'able interface are performed
  25 //   as shutdown-blocking primary sequence tasks.
  26 //   TODO(michaeln): Skip tasks for reading during shutdown.
  27 // * Internal tasks related to committing changes to disk are performed as
  28 //   shutdown-blocking commit sequence tasks.
  29 class CONTENT_EXPORT DOMStorageTaskRunner
  30     : public base::TaskRunner {
  31  public:
  32   enum SequenceID {
  33     PRIMARY_SEQUENCE,
  34     COMMIT_SEQUENCE
  35   };
  36
  37   // The PostTask() and PostDelayedTask() methods defined by TaskRunner
  38   // post shutdown-blocking tasks on the primary sequence.
  39   virtual bool PostDelayedTask(
  40       const tracked_objects::Location& from_here,
  41       const base::Closure& task,
  42       base::TimeDelta delay) = 0;
  43
  44   // Posts a shutdown blocking task to |sequence_id|.
  45   virtual bool PostShutdownBlockingTask(
  46       const tracked_objects::Location& from_here,
  47       SequenceID sequence_id,
  48       const base::Closure& task) = 0;
  49
  50   // The TaskRunner override returns true if the current thread is running
  51   // on the primary sequence.
  52   virtual bool RunsTasksOnCurrentThread() const OVERRIDE;
  53
  54   // Returns true if the current thread is running on the given |sequence_id|.
  55   virtual bool IsRunningOnSequence(SequenceID sequence_id) const = 0;
  56   bool IsRunningOnPrimarySequence() const {
  57     return IsRunningOnSequence(PRIMARY_SEQUENCE);
  58   }
  59   bool IsRunningOnCommitSequence() const {
  60     return IsRunningOnSequence(COMMIT_SEQUENCE);
  61   }
  62
  63  protected:
  64   virtual ~DOMStorageTaskRunner() {}
  65 };
  66
  67 // A derived class used in chromium that utilizes a SequenceWorkerPool
  68 // under dom_storage specific SequenceTokens. The |delayed_task_loop|
  69 // is used to delay scheduling on the worker pool.
  70 class CONTENT_EXPORT DOMStorageWorkerPoolTaskRunner :
  71       public DOMStorageTaskRunner {
  72  public:
  73   DOMStorageWorkerPoolTaskRunner(
  74       base::SequencedWorkerPool* sequenced_worker_pool,
  75       base::SequencedWorkerPool::SequenceToken primary_sequence_token,
  76       base::SequencedWorkerPool::SequenceToken commit_sequence_token,
  77       base::MessageLoopProxy* delayed_task_loop);
  78
  79   virtual bool PostDelayedTask(
  80       const tracked_objects::Location& from_here,
  81       const base::Closure& task,
  82       base::TimeDelta delay) OVERRIDE;
  83
  84   virtual bool PostShutdownBlockingTask(
  85       const tracked_objects::Location& from_here,
  86       SequenceID sequence_id,
  87       const base::Closure& task) OVERRIDE;
  88
  89   virtual bool IsRunningOnSequence(SequenceID sequence_id) const OVERRIDE;
  90
  91  protected:
  92   virtual ~DOMStorageWorkerPoolTaskRunner();
  93
  94  private:
  95
  96   base::SequencedWorkerPool::SequenceToken IDtoToken(SequenceID id) const;
  97
  98   const scoped_refptr<base::MessageLoopProxy> message_loop_;
  99   const scoped_refptr<base::SequencedWorkerPool> sequenced_worker_pool_;
 100   base::SequencedWorkerPool::SequenceToken primary_sequence_token_;
 101   base::SequencedWorkerPool::SequenceToken commit_sequence_token_;
 102 };
 103
 104 // A derived class used in unit tests that ignores all delays so
 105 // we don't block in unit tests waiting for timeouts to expire.
 106 // There is no distinction between [non]-shutdown-blocking or
 107 // the primary sequence vs the commit sequence in the mock,
 108 // all tasks are scheduled on |message_loop| with zero delay.
 109 class CONTENT_EXPORT MockDOMStorageTaskRunner :
 110       public DOMStorageTaskRunner {
 111  public:
 112   explicit MockDOMStorageTaskRunner(base::MessageLoopProxy* message_loop);
 113
 114   virtual bool PostDelayedTask(
 115       const tracked_objects::Location& from_here,
 116       const base::Closure& task,
 117       base::TimeDelta delay) OVERRIDE;
 118
 119   virtual bool PostShutdownBlockingTask(
 120       const tracked_objects::Location& from_here,
 121       SequenceID sequence_id,
 122       const base::Closure& task) OVERRIDE;
 123
 124   virtual bool IsRunningOnSequence(SequenceID sequence_id) const OVERRIDE;
 125
 126  protected:
 127   virtual ~MockDOMStorageTaskRunner();
 128
 129  private:
 130   const scoped_refptr<base::MessageLoopProxy> message_loop_;
 131 };
 132
 133 }  // namespace content
 134
 135 #endif  // CONTENT_BROWSER_DOM_STORAGE_DOM_STORAGE_TASK_RUNNER_